1. Field of the Invention
The invention relates to a telescoping leader for a construction vehicle, for accommodating a vibrator, a pile driver, an earth drilling gear mechanism, or the like.
2. The Prior Art
In the sector of civil engineering, devices of this type are generally known. They serve for driving in or also pulling out pilings, sheet pile walls, pile foundations, or the like, or also for introducing earth bores. For this purpose, the work device, for example a vibrator, is displaceably disposed on the leader, and the leader is used to press a sheet pile wall, for example, into the ground, in a vertical position, and to drive it in to the desired depth. The maximal depth that can be reached this way is determined by the length of the sheet pile wall, and this in turn requires the use of a leader having a sufficient length.
Since the length of the leader should be as short as possible to facilitate transport between the individual construction sites, the use of telescoping leaders has been known for a long time; these leaders are adjustable in their spatial position and attached to a construction vehicle, whereby this term should be broadly understood, in the sense of the invention, since it is supposed to comprise not only road vehicles such as wheeled earth movers or caterpillar earth movers, but also rail vehicles and, for the construction of water structures, also floating bodies, such as pontoons, for example. Fundamentally, the known telescoping leader consists of an outer and an inner leader, which are disposed concentrically or offset relative to one another, and can be displaced relative to one another using hydraulic cylinders or other linear drives. This structure makes it possible to extend the telescoping leader to its maximal height for work use, and to collapse it for transport. Torsion stresses and bending stresses are exerted on the outer leader by the work device, for example a vibrator with a pile-driving profile attached to it, and these stresses are introduced into the construction vehicle by connecting parts.
The disadvantage of the previously known telescoping leaders is that they are very heavy, as the result of open material cross-sections of the inner or outer leader, or an offset arrangement of the inner and outer leader, at the required bending resistance and torsion resistance. As a result, the useful height of the known leaders is restricted.